Many chronic diseases are interrelated and their effects under changing exposures need to be better understood. Policy makers and planners need to understand what the current distributions of avoidable chronic disease are, among whom, and how they are likely to develop in the future, particularly their effect on different populations, what will be the health consequences of the extrapolated trends, and how much these consequences can
be attenuated with what we currently know and might come to know. Modelling the effects by evidence-based extrapolation, incorporating and attributing the epidemiology of related diseases, can give rise to straightforward estimates of incidence and death rates for the most common related conditions for the next 50 years.